<script>
    var a = 'hello'  //字符串 string
    var b = 123 //数字 number
    var c = true // false 布尔类型 boolean
    var d = undefined
    var e = null

    var obj = {//对象 object
        name:'xx',
        age: 88
    }

    var arr = ['a','b','c']
    arr.push('e')
    arr.unshift('0')
    arr.pop()
    arr.shift()
    console.log(arr);
</script>